How cynical am I for thinking this is a brilliantly executed marketing campaign by K-Mart? Google “K-Mart layaway” (without quotes) and you’ll see 650 news links, national and local, all associating this feel-good holiday story with K-Mart. Why would these anonymous Christmas layaway angels not also drop by Wal-Mart or Marshall’s or Best Buy? (To be fair, these reporters at least checked with Wal-Mart, which said it had seen some cases of anonymous charity. But the overwhelming and extremely valuable positive press coverage focuses on K-Mart.)
I am officially calling a special Scrooge Edition Bullshit. Please Santa prove this cynic wrong.
containseggs 
You’re not the only one. I just saw a K-mart ad about this on Hulu and thought “that’s a nice way to get around those ‘no purchase necessary to win’ laws.” So I searched for “k-mart layaway angles bullshit” since attaching “bullshit” to a search seems to be the best way to get to the bottom of things. The number of news stories that came up in the results is weird, as is the number of examples in the article you linked to. Did someone know that they were going to make news about this, and so they’ve been keeping lists? …and to what degree is your average layaway department set up to handle someone who walks in and says “I want to pay off some random people’s layaway accounts.”
It’d be nice if this were a spontaneous thing that has happened, but it seems incredibly suspicious, particularly with K-mart buying ads to advertise it.